Method of rolling tubes.



A. PASSL. METHOD or ROLLING TU-BES.

APPLICATION FILED OUT. 26, 1905.

VAX

Patented Apr. 4,1911.

PATENT OFFICE.

ALOYS FASSL, OF DINSLAKEN, GERMANY.

METHOD OF ROLLING TUBES.

Specification of Letters Patent.

Patented Apr. 4, 1911.

Application filed October 26, 1905. Serial No. 284,532!

To all whom 'it may concern:

I Be it known that I, AnorsFAssL, a citizen of the German Empire, and resident of Dinslaken, Rhine Province, Germany, engineer, have invented new anduseful Improvements in Methods of Rolling '.l"ubes,'of which the following is a specification.

In the method of rolling tubes, when the so called continuous rolling-mills are used, a special groovin is employed in order to move the mandre which passes freely with the material through the rolling mill at the same speed as the circumferential speed ot' the-last pair of rolls. first pair of rolls have oblate passes, and the last pair have circular passes. As the speed of the mandnel and the circun'iferential speed are equal, the mandrel must .be equal in length to the rolled out tube. To roll out long tubes, long mandrels must be used which besides being very unwieldly, often cause great difiiculties when pulling the rolled out tubing from the mandrel, These disadvantages are avoided by providing the rollers with grooves described hereinafter, and the pulling ofil of the rolled out tubing from the mandrels is much facilitated and the cost of the mandrels greatly-reduced. The passes of all rolls have an oblate form, those of the first pair of rolls being less than those of the last pair of rolls. Bythus grooving the rolls, the mandrel cannot move forward with the circumferential speed of the last pair of rolls but with little if any more than the circumferential speed of the first pair of rolls. The material being rolled is moved .forward on the smopth mandrel by means of thc' fi'iction in'the passes of the last pair of rolls whichare kept rough, and the mandrel moves on at little if any more than the speed of the roll-passes'of the first pair of rolls, because a' greater friction is produced in these than in the last pair of rolls, firstly, on.

account'oli the slight'oblateness of the pass of the first pair of rolls, and secondly bccause otthe considerable reduction of material between the mandrel and the final for'lastpair of rolls. Therefore the mandrel lschiickcd aflittle during the rolling, in comparison-with the material being rolled and 1 little longer than the rolling 1- of rolls would require. 'Thus it. the first riills have only the half or a third For this purpose, the

- l of the circumferential speed of the last rolls,

| the mandrel can be correspomlingly shorter only a little being added for the entire rolling out at the end of the rolling process. 'As mandrcls are liable to wear out and must be continually renewed, short mandrels are a great saving. By the oblate form of the pass between the last pair oi'rolls, the rolled out tubing; is also oblate and so can be .very easily pulled olltrom the mandrehwhich is not. the case withthc round passes.

in the accompanying drawing, Figure 1 shows such an arrzmgclnenti of rolls, the mathe manner described. Fig. 2 represents the forms of the in Fig. 1.

It is shown that the mandrel in the first pair of rolls is completely surrounded by the material, on the one hand by the comparatively slight oblatcness of the passes, and on the other hand, by the considerable reduction of material being rolled, therefore the friction between the n'mndrel and the materialis much greater thanin the last pair of -lOll-ShVlllt'l'l, owing to the oblateness of the passes, loosens the material sidcwise from the mandrel, thereby reducing the friction and cltccting a forward movement of the material cori'espimding to the circumferential speed of the rolls a, I), while the mandrel can follow only at the average circumferential speed of the rolls d, 6.

Having thus fully described my invention .what I desire to secure by Letters Patent is:

The method of rolling tubes in a continuous mill from a longitudinally apertured blank over a mandrel capable of m0ven'icnt in the direction of rolling as the same progresses, which consists in subjecting the blank, when assembled on the mandrehto a rolling action in said mill, and decreasing the contacting area of the successive passes ,in the mill. and the cross sectional areaof the blank, sothat the speed of the mandrel imparted through the work by the rollsat the entering end' of the mill.-

\V LLIAM Knnrrnns, Jon. Sonora.

terial having been rolled on the n'landrel in passes of the rolls illustrated is determined and controlled by the friction on v 

